OpenGL: Fix Custom Shaders (#7697)

Ref: GitHub Discussion #7696 

See commit messages for details.

src/renderer/OpenGL.zig

@@ -395,7 +395,7 @@ pub inline fn textureOptions(self: OpenGL) Texture.Options {
     _ = self;
     return .{
         .format = .rgba,
-        .internal_format = .srgba_compressed,
+        .internal_format = .srgba,
         .target = .@"2D",
     };
 }
@@ -428,7 +428,7 @@ pub inline fn imageTextureOptions(
     return .{
         .format = format.toPixelFormat(),
         .internal_format = if (srgb) .srgba else .rgba,
-        .target = .Rectangle,
+        .target = .@"2D",
     };
 }
 

src/renderer/shaders/glsl/bg_image.f.glsl

@@ -4,7 +4,7 @@
 // so as to align with our texture's directionality.
 layout(origin_upper_left) in vec4 gl_FragCoord;
 
-layout(binding = 0) uniform sampler2DRect image;
+layout(binding = 0) uniform sampler2D image;
 
 flat in vec4 bg_color;
 flat in vec2 offset;
@@ -23,7 +23,7 @@ void main() {
     // size of the texture to the dest rect size.
     vec2 tex_coord = (gl_FragCoord.xy - offset) * scale;
 
-    vec2 tex_size = textureSize(image);
+    vec2 tex_size = textureSize(image, 0);
 
     // If we need to repeat the texture, wrap the coordinates.
     if (repeat != 0) {
@@ -38,7 +38,8 @@ void main() {
     {
         rgba = vec4(0.0);
     } else {
-        rgba = texture(image, tex_coord);
+        // We divide by the texture size to normalize for sampling.
+        rgba = texture(image, tex_coord / tex_size);
 
         if (!use_linear_blending) {
             rgba = unlinearize(rgba);

src/renderer/shaders/glsl/bg_image.v.glsl

@@ -1,6 +1,6 @@
 #include "common.glsl"
 
-layout(binding = 0) uniform sampler2DRect image;
+layout(binding = 0) uniform sampler2D image;
 
 layout(location = 0) in float in_opacity;
 layout(location = 1) in uint info;
@@ -64,7 +64,7 @@ void main() {
     repeat = info & BG_IMAGE_REPEAT;
 
     vec2 screen_size = screen_size;
-    vec2 tex_size = textureSize(image);
+    vec2 tex_size = textureSize(image, 0);
 
     vec2 dest_size = tex_size;
     switch (info & BG_IMAGE_FIT) {

src/renderer/shaders/glsl/image.f.glsl

@@ -1,6 +1,6 @@
 #include "common.glsl"
 
-layout(binding = 0) uniform sampler2DRect image;
+layout(binding = 0) uniform sampler2D image;
 
 in vec2 tex_coord;
 

src/renderer/shaders/glsl/image.v.glsl

@@ -1,6 +1,6 @@
 #include "common.glsl"
 
-layout(binding = 0) uniform sampler2DRect image;
+layout(binding = 0) uniform sampler2D image;
 
 layout(location = 0) in vec2 grid_pos;
 layout(location = 1) in vec2 cell_offset;
@@ -32,11 +32,12 @@ void main() {
 
     // The texture coordinates start at our source x/y
     // and add the width/height depending on the corner.
-    //
-    // We don't need to normalize because we use pixel addressing for our sampler.
     tex_coord = source_rect.xy;
     tex_coord += source_rect.zw * corner;
 
+    // Normalize the coordinates.
+    tex_coord /= textureSize(image, 0);
+
     // The position of our image starts at the top-left of the grid cell and
     // adds the source rect width/height components.
     vec2 image_pos = (cell_size * grid_pos) + cell_offset;